The present invention is directed to an electronic device used to trigger a safety device such as an inflatable retention device for use in a motor vehicle.
A device of the above-described type is known from 1141 Ingenieurs de l'Automobile (1982) No. 6, pp 69 to 77. It is of significant importance for electronic devices of this type that all structural elements, which are critical for the functioning of the device, be able to be tested. Only in this way can one ensure a high degree of operational reliability, which is necessary for safety devices of this type. From DE-A 22 22 038, it is known, in testing the firing element of such a device, to connect a constant-current source to the firing element and to provide a differential connection for measuring the voltage drop across the firing element. This approach requires additional switching devices, which are provided for testing purposes, apart from the triggering means of the firing elements. Furthermore, a disadvantage of the known devices is that the firing elements are connected in a two-pole fashion, with power output stages applied to them, so that the danger of unintentionally activating the firing elements as, for example, during testing or assembly work cannot be completely ruled out. Finally, it is only possible to test the output stages controlling the firing elements with the use of an additional mechanical switch, which disconnects the power outputs from the electric power supply under normal operating conditions, as, for example, when there is no imminent danger. The ON state of this mechanical switch, however, cannot be easily checked.